DESCRIPTION: This project will identify the acoustic and articulatory features of the (mis)perceptions of speech sounds made by individuals with hearing loss who use hearing aids and cochlear implants. The project will also investigate the effects of signal modifications designed to overcome these misperceptions. Two procedures will be used to identify the frequency regions of and types of errors that these listeners make. The first procedure, the correlational method, is a new technique that yields rapid and reliable estimates of how listeners use various frequency regions and features of speech. This method holds considerable promise for use in clinical testing, the design and fitting of hearing aids, and also for evaluating and programming processors in cochlear implant patients. The second procedure, testing with filtered speech, is a more time-tested method, yielding much the same information, but in a longer and less efficient fashion. In the proposed experiments, these two methods will be used in conjunction to test the validity of each. In addition, both methods can be used to test hypotheses concerning the degree of hearing loss and the ability of patients to use audible speech information. If warranted, the correlational method will be further developed for clinical application. The information obtained from the correlational method applied to hearing-impaired patients will suggest some signal modifications and strategies for hearing aids and cochlear implants. Additional experiments will test the efficacy of these strategies upon speech recognition in listeners with sensorineural hearing loss.